Brake-shoe.



J. M. GRIFFIN.

` BRAKE SHOE.

APPLICATION FILED JAN. 191' 1914.

. 1,093,776. Patented Apr.21,1914

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- sTaTns PATENT OFFICE.

JUDSON IVI. GRIFFIN, OF DETROIT, MICHIGAN.

BRAKE- SHOE.

To all who/m, 'it may concern Be it known that I, JUDsoN M. GRIFFIN, a citizen of the United States, residing at Detroit, county of Wayne, State of Michigan, have invented a certain new and useful lmproveinent in Brake-Slices, and declare the following to be a full, clear, and eXact description of the same, such as will enable others skilled in the art to which it pertains to make and use the saine, reference being had to the accompanying drawings, which forni a part of this specification.

This invention relates to brake-shoes and especially to brake-shoes carrying abrading material and comprising a shell divided into pockets that are alternately filled with abrading material sol as to leave alternate vacant pockets.

My invention is intended as an improvement on the brake-shoe shown in the Hoffman Patent No. 605,056.

The improvement consists of providing means whereby the vibration of the pocket partitions is lessened. T his avoids loosening the abrading material and also, frequently, the fracture of the shell. n

In the drawing, Figure l, is a perspective of an abrading brake-shoe, two of the abrading material containing pockets being shown with the abrading material and the third pocket being shown empty. Fig. 2, is a longitudinal section of the same on a smaller scale.

Brake-shoes such as shown in the Hoffman patent have met with considerable success in truing wheels. Heretofore these brakeshoes have always been made with the shell and cross partitions without any eifort being made to interpose webs. When brakeshoes of this type were first introduced, car wheels were usually made of chilled iron instead of steel, as many are today, and wheels were very much lighter than at the present time. Car wheels in the early day of this brake-shoe had treads of from an inch to two inches, while today treads of from three to four inches in width are very common; what is more, very much heavierl cars are used upon the traction railways of our cities; interurban electric cars have come into general use and heavier cars upon railroads have been coming into use. Much heavier loads increase very materially the inertia forces that have to be resisted by the brake in stopping the oar or train. With these more diihcult working conditions it Specification of Letters Patent.

Application led January 19, 1914.

Patented Apr. 21, 1914.

Serial No. 812,917.

was found that the shells fracture very frequently and this has been a difficulty which manufacturers of this type of brake-shoe have been obliged to meet in the last decade and were at a loss to know how to get around it.

The shells must be capable of wearing down with the abrading material and hence it is made to have as little shell exposed to friction with the wheel as possible. To make it possible for the shell to keep pace with the wear of the abrading material the shells are constructed of a very soft gray iron. It is found by actual experience that the partitions can not be made much thicker than they have always been made without presenting too much iron to the periphery of the wheel. One of thelirst methods that was suggested for meeting this fault was to increase the width of the partitions, but this was found to be unsatisfactory for the reason already given.

The fracture of the partitions was not the only difficulty that the brake-shoe makers were obliged to meet but what proved even a greater difficulty was the tendency of the abrading material to loosen about the partition walls, especially the partition walls which were inclined away from the direction in which the wheel was rotating.

It has been found most expedient in the retaining of the abi'ading block in position to make the partition walls slope slightly so the walls of the abrading material containing pockets tend to converge. This forms a sort of dove tail to hold the abrading material in. In this convergence one of the walls will incline slightly toward the direction of rotation as the wall a in Fig. 2 and the other wall, as in Fig. 2, will incline slightly away from the direction of rotation, considering the direction of rotation to be in the direction of the arrow of this figure. It is well known that a plane surface held against a circular revolving member will be vibrated or jarred more seriously when the surface is tipped slightly against the rotating member, while if it is tipped with the rotating inember the effect of the rota-ting member is less jarring but more in the way of plain friction. This is the condition with the partition wall b. It is set in vibration by being tipped against the rotating element. This vibration is suiiicient to loosen the abrading material about it so that the effec-t of the slight incline as a dove tail to hold the block llO in is impaired. Very often the block starts -to work out. This fault has long been noticed but has not always been understood. I have conceived the idea oi' remedying this fault by practically stopping the vibration. As yalready pointed outthe thickened partition walls were tried but these merely tended to prevent the fracture of the partition walls. This only eliminated vibration in a slight degree, for with the wider treads the partition walls were made so long that they were ibound to vibrate when held against the rotative element. The use of iron blocks or inserts driven in between the partition walls of the clearance pockets has been suggested but found practically impossible on accounte of presentingtoo much iron surface to the periphery ot' the wheels. I overcome the ditliculties already alluded to by the simple structure shown in the drawing.

The shell c and the partition walls a and l) are substantially the same as have been in use since the Hoffman patent. I locate in the vacant pockets a pair of triangular braces Z that run together' at their meeting ends forming a sort of crescent. These braces are a part of the casting. They are located at vthe points of the partition that, when the shoe is in position against the wheel adjoins the line of jointure between the flange and the tread of the wheel. After considerable experimentation with wheels and lbrake-shoes I have found that this is the point subject to the greatest torsional and transverse strains. In the end abrading material containing pockets I locate a single triangular brace e to brace the end walls of the shell. These webs or braces are made triangular so as to present as little metal as possible to the wheel for wear.

That I claim is:

l. An abrading brake shoe, comprising a shell with a plurality of cross partitions forming one or more abrading material containing poclets and one or more vacant pockets, integral braces for preventing vibration and fracture of the partition walls, and abrading material contained in the abrading material containing pockets.

2. An a'brading brake-shoe, comprising a shell provided with a plurality oi transverse partitions dividing the shell into one or more abrading material containing` pockets and one or more vacant pockets, integralk braces contained in the vacant pockets for bracing the partition walls to prevent vibration or fracture, and abrading material contained in the abrading material containing pockets.

3. An abrading brakeshoe, comprising a shell provided with transverse integral partitions dividing the shell into one or more abrading material containing pockets and one or more vacant pockets, integral braces in the vacant pockets comprising double triangular webs running together at their meeting ends, and abrading material contained in the abrading material containing pockets.

-l. An abrading brake-shoe, comprising a shell lmving integral cross partitions dividing the shell into one or more abrading material containing pockets and one or more vacant pockets, said partitions of the abrading material containing pockets being slightlyv converging to form a dove tail, abrading blocks contained in said abrading material pockets and held therein h v the dove tail lock, and integral braces attached to the partition walls of the abrading material containing pockets.

An abrading brake-shoe, comprising a shell having integral cross partitions dividing the shell into one or more abrading ma terial containing pockets and one or more vacant pockets, said partitions being cut away at one end to accommodate the wheel fiange, integral bracing webs connecting the partition walls and the back of the shell, the said integral bracing webs beinglocated adjacent the inside end of the llangecut in the partition.

In testimony whereof, I sign this specili cation in the presence of two witnesses.

JUDSON M. GRIFFIN.

IVitnesses STUART C. BARNES, MARIETTA E. RUDD.

Copies of this patent may be obtainedifor ve cents each, by addressing the Commissioner of Patents Washington, D. C. 

